Hydraulic damper control



Sept- 14, 1954 w. M. SMITH ETAL HYDRAULIC DAMFER CONTROL Filed OCT.. 5, 1950 jy k///WV Patented Sept. 14, 1954 HYDRAULIC DAlWPER CONTROL William M. Smith, Glen Ellyn, and Charles E.

Krupp, Evanston, Ill., assignors to Vapor Heating Corporation, Chicago, Ill., a corporation of Delaware Application October 5, 1950, Serial No. 188,618

(Cl. 23S-35.3)

1l Claims.

This invention relates generally to temperature control systems and more particularly to an electric circuit and an apparatus associated therewith for automatically adjusting a plurality of valves, for example air dempers or ventilators for controlling ambient temperatures at predetermined locations.

lThe improvements of the present invention are suitable for use in any situation in which an ambient temperature can be controlled by selectively operating one or more of a plurality of valves, dampers, etc. However, for the purpose of showing one specic use of the invention, it is shown herein as a means for automatically adjusting the ventilator shutters for varying the amount of air delivered to the cooling systems for the engines of a diesel-electric locomotive. The power units of such locomotives ordinarily includes two engines and it is desirable to so control the delivery of air to their cooling systems as will insure operation of both engines at an optimum elhciency.

It is sometimes the practice to provide such engines with a main radiator and an auxiliary radiator. In such case, the main radiator, associated with each engine, is regulated by a main shutter associated therewith and the auxiliary radiators for both engines may be supplied with cool air from a single shutter.

riihe present invention, therefore, provides means whereby the temperature of each engine, in addition to controlling its main radiator, will also exercise control over the auxiliary shutters.

According to the present invention, the main shutter of each engine is controlled by a circuit responsive to the condition oi such engine, and concomitantly the auxiliary set of shutters for its auxiliary radiator may likewise be controlled, the circuit being so designed that once control is effected over the main shutter of one engine together with the auxiliary shutter, a changing temperature condition of the other engine is able to aiiect its main shutter only and is not able to affect the condition of the auxiliary shutter. The present invention is further characterized by a fluid pressure system including a pump and a motor which are required to be operated only when the shutters are to be operated in accordance with a temperature condition.

A principal object of the invention, therefore, is to control temperature responsive mechanisms, consisting of a pair of main temperature responsive devices and an auxiliary temperature responsive device, in accordance with a temperature condition at two stations, or two temperature measuring points, each station controlling a main temperature responsive device and under certain auxiliary temperature responsive device, the control of said auxiliary temperature device by one of said stations being thereafter unaffected by any control by the other of said stations, until the rst station no longer controls said auxiliary temperature responsive device.

Other objects and important features of the invention will be apparent from a study of this specication, taken with the drawing, which together illustrate a preferred embodiment of the invention and what is now considered to be the best mode of applying the principles thereof. The scope of the invention is intended to be defined by the scope and breadth of the appended claims rather than the specific structures and use thereof described herein.

ln the drawing, the single gure is a circuit diagram illustrating a control system for the main and auxiliary shutters of the radiators of a twin engine diesel-electric locomotive unit.

Referring now to the drawing, the control system according to the present invention, is shown as being adapted to control a main shutter i@ of a main radiator, not shown, of a `first engine; a main shutter il of a main radiator, not shown, of a second engine; and an auxiliary shutter l2 of the auxiliary radiators of both the rst and second engines.

The temperature or other running condition of the first engine is measured by a rst thermostat I3, and the temperature or other running condition of the second engine is measured by a second thermostat I4.

The main and auxiliary shutters IG, II and I2 are operated by uid under pressure supplied by a pump lli driven by a motorr II which is connected in circuits including the thermostats I3 and IAl. The motor I'i is controlled by the thermostats I3 and I4, and the pump i6 thus supplies pressure fluid to a pressure line I8 having lines i9, 2@ and 2l branching therefrom. The pressure uid is directed past normally-closed solenoid-operated inlet valves 22, 23 and 2t to operate single-acting, spring-return fluid motors :26, 2 and 28 which are connected through suitable linkages 29, 31B and 3l to operate the shutters it, il and I2. The operation of the uid motors 2d, 2l and 28 is controlled in part by normally-open solenoid-operated exhaust valves 32, 33 and 3ft connected to their associated iluid motors by iiuid lines 3S, 31 and 38 respectively. Each exhaust valve 32, 33 and 3ft is connected by a return line 39 to a sump or reservoir 4I.

The pressure of the fluid delivered by the pump Iii may be regulated or relieved by a relief valve l2 connected in a relief line i3 branching from the pressure line I8 and connected to the return line 39 to the sump 4I. The pump is supplied from the sump 4l by an intake line lili.

Each thermostat I3 and Ill is operable to control relays which in turn control the motor il', the inlet valves I9, 20 and 2l and the exhaust Valves 32, 33 and 34. Thermostat It is thus connected to control a pair of relays 46 and 41 which control the motor I1, main shutter I9 and auxiliary shutter I2. Thermostat I4 is thus also connected to control a pair of relays 48 and 49 which control the motor I1, main shutter I i and auxiliary shutter I2.

It should here be noted, that when relays 46 and 41 are operable to control the auxiliary shutter I2, no condition of the thermostat I4, in operating relays 48 and 49 will affect the operation of the auxiliary shutter I2. Conversely, when relays 48 and 49 are operable to control the auxiliary shutter I2, no condition of the thermostat I3, in operating relays 41 and 48, will aiect the operation of the auxiliary shutter I2. The details of the circuits accomplishing the above kfunction will appear as this specification proceeds.

The control system according to the present invention is designed to maintain the main and auxiliary shutters in closed position if the engine is not up to proper running temperature. The thermostat I3 for the first engine is of the mercury column contact type, and includes a continuous contact 5I, a low heat contact 52, and a high heat contact 53. When the top of the mercury column lies below contact 52, the relays 48 and 41 are energized.

The circuit energizing relay 46 includes a positive line P, buffer resistor 54`, winding 56 of the relay 46, and then a lead 51 to the negative line N. The circuit energizing relay 41 includes positive line P, buffer resistor 58, lead 59, lead 6I, winding 62 of the relay 41 and thence by the lead 51 to the negative line N.

When the relay 46 is thus energized, circuits are opened which control the operation of the motor I1 and the inlet valves 22 and 23. The circuit to the motor I1 includes positive line P, a contact 63 of the relay 46, a lead 64 and a lead 66 to the negative line N. The circuit to the inlet valve 22 for the main shutter I9 of the first engine radiator includes positive line P, a contact 61 of the relay 46, a lead 68, solenoid winding 69, a lead 1I and lead 66 to negative line N. The circuit to the inlet valve 23 for the auxiliary shutter I2 includes positive line P, a contact 12 of the relay 46, a lead 13, branching lead 14, solenoid winding 16 of the valve 23, a lead 1'? and lead 66 to the negative line.

When the relay 41 is thus energized, circuits are opened which control the operation of the exhaust valves 32 and 33. The circuit to the exhaust valve 32 of the main shutter I0 of the first engine radiator includes a lead 18 from the supply line, a contact 19 of the relay 41, a lead 9| to a solenoid winding 82 of the exhaust valve 32, and thence by a lead `83 to the negative line. The circuit to the exhaust valve 33 of the auxiliary shutter I2 includes the positive line P, lead 18, a contact 84 of the relay 41, a lead 66 to a solenoid 81 of the exhaust valve 33, and thence by a lead 88 to the negative line.

Under the condition described above, the fluid motors 26 and 21 are ported to the return line 39 of the fluid pressure system, since the exhaust valves 32 and 33 are open when their solenoids are de-energized. Under this condition the inlet Valves 22 and 23 are closed since their solenoids are de-energized, and they block the flow of the pressure iiuid, if any, to the fluid motors 26 and 21. Since the fluid motors 26 and 21 are of the single-acting, spring-return type, their action is such as to return any fluid therein to the return line 39, and it will be apparent that the shutters 4 I0 and I2 will close on the return stroke of the iiuid motors 26 and 21.

The relays 46 and 41 carry contacts for closing circuits to apply heat to the thermostat I3 to change the condition of the relays 45 and 41, and place the valves controlling the operation of the 'shutters in condition for operation thereof. The `relay 46 when energized as described above closes a circuit containing a contact 89, a lead 9|, a cycling resistor 92, a lead 93, a heat coil 94 of the thermostat I3, and thence by a lead 96 connected to the lead 51 to the negative line. The cycling resistor 92 is so designed as to give 2 of heat on the coil 94 when the relay contact 89 is closed. The relay 41, when energized as described above, closes a circuit containing positive line P, lead 18, contact 91, cycling resistor 98, the lead 93, heater coil 94 and the leads 9G and 51 to the negative line N. The cycling resistor 98 is alsofso designed as to apply 2 of auxiliary heat on the coil 94, and it will be apparent that the closing of the two circuits just described will give 4 of auxiliary heat to the thermostat I3.

The heating elect just described will raise the mercury column inV the thermostat I3 until it touches the contact 52. It will be seen that a short circuit will be then made to cle-energize the relay 41, consisting of positive line P, limiting resistor 58, lead 59, the mercury column between contacts 5I and 52, lead 69, and thence by the lead 51 to the negative line N. The short circuit thus made will de-energize the lwinding 62 of the relay 41`thereby closing contacts 19 and 84, and opening contact 97. The winding 56 of relay 46, however, will remain energized, since the circuit therethrough will be maintained.

Under this condition of the relay 4'?, the coil 82 of the exhaust valve 32'will be energized thereby closing valve 32, and the coil k8'! of exhaust valve 33 will also be energized thereby closing same.

However, contact 91 of relay 41 will be opened thereby reducing the amount of heat on the heater coil 94 of thermostat I3 by 2 and it will be apparent that contact 89 of relay 46 will remain closed to supply 2 of heat to the heater coil 94.

Since the condition of relay 46 is unchanged, the circuits to motor I1 will remain in open condition, and the inlet valves 22 and 29 will remain closed since their respective solenoidsl 69 and 'i5 will be de-energized. Since the fluid Within the fluid motors 26 and 21 has been already exhausted the shutters I0 and I2 will remain closed.

The presence of 2 of heat on the heater coil plus the heating eiiect of the coolant of the rst engine may raise the mercury column in the thermostat I3 until it makes Contact with the contact 53. Under this condition a short circuit is made which de-energiz'es the winding 56 of relay 46, said circuit consisting of the positive line P, limiting resistor 54, lead I9! to contact 53, the mercury column between contacts 53 and 52 and thence by leads 99 and 51 to the negative line N.

With winding 56 of relay 46 thus cle-energized, contacts 63, 61 and 12 will close, while contact 89 thereof will open. The closing of contact 63 will energize motor I1 to drive pump I6 to furnish fluid under pressure to operate the iluid motors 26 and 21, at the same time completing a ground circuit for valves 22 and 23.4 The closing of contact 61 will open inlet valve 22 and operate fluid motor 26 to open the main shutter I0, it being remembered that exhaust valve 32 remains closed to hold the pressure fluid within the uid motor 26. The closing of contact 12 will open inlet valve 23 and operate fluid motor 21 to open the auxiliary shutter I2, it being remembered that exhaust valve 33 remains closed to hold the pressure iiuid within the iuid motor 21.

The opening of contact 89 will completely cut of? the heat from the heater coil 94 of thermostat I3, and if the engine temperature is not high enough to hold the mercury column up to the contact 53 the relay 46 will once more become energized, thereby opening contacts 63, 61 and 12 which will close valves 22 and 23 and trap pressure fluid in the fluid motors 26 and 21 to hold the shutters I and I2 open. The circuit to motor I1 will thus be opened thereby stopping the pump I6 and minimizing wear thereof.

The contact 89 will once more be closed to apply 2 of heat to the thermostat I3 thereby repeating the operation of supplying pressure fluid to the motors 26 and 21 through the inlet valves 22 and 23.

The main shutter of the other engine radiator is under the control of the thermostat I4, and under conditions as will be described, the auxiliary shutter I2 is also under the control of the thermostat I4, provided thermostat |3 is not controlling the auxiliary shutter I2.

The thermostat |4 of the second engine is of the mercury column contact type, and includes acontinuous contact |02, a low heat contact |03, and a high heat contact |04. The relays 48 and 49 are adapted to be energized when the mercury column or thermostat I4 lies below conta-ct |03, and the circuit energizing relay 48 under such condition of the thermostat I4 includes positive line P, limiting resistor |06, lead |01, Winding |08 of the relay 46, and thence through lead |09 and the lead 51 to the negative line N. The circuit energizing relay 49 inoludes'the positive line P, limiting resistor |00, lead |05, winding I I9 of the relay 49, lead ||5 connected to the lead |09, and thence to the negative line N by the leads |09 and 51.

When the relay 48 is thus energized, circuits which control the operation of the motor |1 and the inlet valves 23 and 24 are opened. The circuit to the motor |1 includes positive line P, lead contact II2 of the relay 48, lead I|3, lead 64, and the lead 66 to the negative line N. The circuit to the inlet valve 24 for the other main shutter includes positive line P, the lead III, a contact ||4 of the relay 48, a lead II6, solenoid winding |I1 of the inlet valve 24, and a lead IIB and 66 to the negative line N. The circuit to the inlet valve 23 of the auxiliary shutter I2 includes positive line P, the lead I I I, a contact I|9 of the relay 48, a lead I2|, the lead 14, solenoid winding 16 of the inlet valve 23, and the leads 11 and 60 to the negative line N.

It will be noted that contacts 63 and I2 are in parallel across the supply line and that the motor I1 will be energized when either relay 46 or 48 is de-energized. Likewise, contacts 12 and ||9 are in parallel across the positive and negative lines and the solenoid 16 auxiliary inlet valve 23 will be energized when either relay 46 or 48 is de-energized. It will also be noted that the main shutter inlet valves 22 and 24 are under control by their respective relays 46 and 48 only.

When the relay 49 is thus energized, circuits which control the operation of the exhaust valves 33 and 34 are opened. The circuit to the exhaust valve 34 of the main shutter of the second engine includes a lead |22 from the supply line, contact |23, a lead |24, a solenoid |26 of the exhaust valve 34, and a lead |21 to the other side of the supply line. The circuit to the auxiliary shutter exhaust valve 33 includes the lead |22, a contact |28 of the relay 49, a lead |29, the lead 86, the solenoid 81 of the exhaust valve 33, and the lead 88 to the other side of the supply line.

Under the condition just described for the relays 48 and 49, the fluid motors 21 and 28 are ported to the return line 39, since both are open when their solenoids are de-energized. Under this condition, the inlet valves 23 and 24 are likewise closed, since their solenoids are de-energized, thus blocking the flow of fluid to the motors 21 and 38. It will be apparent that the shutters Il and I2 will be closed by the action of the return springs of the motors 21 and 28. It will be apparent, also, that if thermostat I3 is calling for auxiliary shutter I2 to remain open, such demand will govern, instead of the demand of thermostat I4, calling for the shutter |2 to remain closed.

The relays 48 and 49 carry contacts for the application of heat to the thermostat I4 to change the condition of the relays 48 and 49 and place the inlet valves 23 and 24 and the exhaust valves 33 and 34 in condition for operation of the shutters Il and I2. The relay 48 When energized as described above closes a circuit containing the lead III, a Contact |30, a limiting resistor ISI, a lead |32, a heater coil |33 of the thermostat I4,

, and a lead |34 to the other side of the supply line. The limiting resistor |3| is so designed as to give 2 of heat on the coil |33. The relay 49 when energized as described above closes a circuit containing the lead |22, a contact |31 of the relay 49, a limiting resistor |38, vthe lead |32, heater coil |33, and the leads |34 and 51. The limiting resistor |38 is also designed as to give 2 of heat on the coil |33, and it will be apparent that the closing of the two circuits just described will give 4 of heat to the thermostat I4.

rlhe heating eect will raise the mercury column in the thermostat I4 until it touches the contact |03, which may be considered the normal heat point for the engines. It will be seen that a short circuit will be made to de-energize the relay 49, consisting of the limiting resistor |00, lead |05, a lead |20, the length of the mercury column between contacts |92 and |03, a lead |25, and thence by the leads |09 and 51 to the other side of the supply line. The circuit thus made will de-energize the winding |I0 of the relay 49 thereby closing contacts I 23 and I 28 and opening contact |31.

It will be noted that contact 84 of relay 41 and contact I 28 of relay 49 are connected in parallel across the supply line and that the solenoid 81 of the auxiliary shutter exhaust valve 33 will be energized when either contact 84 or contact |28 is closed. It will thus be apparent that if either thermostat I3 or 4 is at normal heat condition the exhaust valve 33 will be closed.

The de-energization of relay 49 will open contact |31 to reduce the amount of heat on the heater coil I 33 by 2, and it will be apparent that Contact I 3| will remain closed to continue to supply 2 of heat to the heater coil |33.

Since the condition of relay 48 is unchanged, the circuits to motor I1 will remain unchanged as respects the thermostat I4, and the inlet valves 23` and 24 will remain closed since their respective solenoids 16 and ||1 will b e de-energized. Since the fluid within the fluid motorsfZ'i andZiihas been exhausted by the exhaust valves,l the shutters i i and E2 will remain closed.

lt should be noted, however, that inlet valve 23 and exhaust valve 33 are also under the control of the relays lo and 4l', and if the thermostat i3 is at high heat the valves 23 and 33 will be under the control of said thermostat irrespective of the condition of thermostat I4.

rhe presence of 2 of heat on the heater coil 33 plus the heating effect of the coolant of the second engine may raise the mercury column in the thermostat le until it makes Contact with the contact Hill. Under this condition a short circuit is made which de-energizes the winding E93 of relay e3, said circuit consisting of limiting resistor lee, lead lill, a lead lSS, the length of the mercury column between contacts its and the lead R25, leads 5&9 and 5l' to the other side of the supply line.

When the Winding I-QS'of relay i8 is thus deenergized, contacts I i2, Ht and H9 will close, While contact 53| Will open. The closing of contact il? Will energize motor il to drive the pump at the Sametime completing a ground for the inlet valves 233 and 24. The closing of contact ill-l will open the inlet valve 24 for the shutter I E ci the second engine, and fluid will pass therethrough to operate the fluid motor 2B, it being remembered that exhaust valve 34 remains closed to hold the pressure fluid within the fluid motor 23. The closing of contact H9 will open inlet valve and operate fluid motor 2l to open auxiliary shutter i2, it being remembered that exhaust valve 33 remains closed to hold the pressure huid Within the fluid motor 2l.

The opening of contact BSI by the shunting out of relay i8 Will completely cut off the heat from the heater coil 33 of thermostat i4, and if the temperature of the second engine is not high enough to hold the mercury column up to the Contact 84, the relay i8 will once more become energized, thereby opening contacts M2, H and i E9 to close valves 23 and 2t and trap uid in the fluid motors 21 and 23 and hold shutters II and I2 open. The circuit to motor il will thus be opened thereby stopping pump IS.

The contact 53| will once more be closed to apply 2 of heat to the thermostat iii, thereby repeating the operation of supplying pressure fluid to the motors 2l' and 23 through the inlet valves 23 and 24.

Assuming a condition where the rst engine is' operating at normal heat with the mercury in the thermostat I3 between contact points 52 and 53, and where the second engine is running hot with the mercury in thermostat i4 making contact with the contact m4, the following conditions will obtain. Under this condition, and as has been previously described in detail, relay 46 Will be energized While relay di Will be cie-energized. Relays 48 and 4S under this condition will both be cle-energized. This will cause motor I'I to start and supply fluid under pressure. Valve 34 will close, while valve 24 will open to supply pressure fluid to open main shutter I I. Valve 33 will likewise close, while valve 23 will open to open auxiliary shutter i2. Valve 22 will close, While valve 32 will remain closed thus trapping the pressure fluid in duid motor 23 to maintain shutter lil open. It will be remembered that relay 4B will continue to supply 2 of heat to heater coil 94 and thus attempt to raise the mercury column in thermostat I3 to cle-energize relay 46.

Under this condition of the thermostat I3, the

8 relays 46and 4"! would normallylcall for a 'similar operation of the valves 23 and 24 'as the valves 22 and 23, but it will be remembered that the relay Iltis now controlling valve 23 and that relay 49 is now controlling valve 33. Likewise, relay 48, instead of relay 46, is controlling the operation of motor I'I. Obviously, the conditions obtaining Where the rst engine is at high heat, and the second engine is at normal heat are reversed as respects the control relays v46, 41, 48 and 49.

Itwill thus be seen that the engine operating at high heat is controlling of the condition of the auxiliary shutter as Well as the condition of its main shutter. It Will also be seen that the thermo'stats I3 and I4 constantly maintain lthe ternperature of each engine at suchA a value as to promote maximum emciency. In opening the shutters, both main and auxiliary, for cooling, the possible over-cooling effect is also corrected by the thermostats, the amount of corrective heat being varied in accordance with the amount of cooling obtained by the shutters.

While the invention has been described in terms oi a preferred embodiment thereof, it is intended that the invention beilimit'ed only by the terms of the claims here appended;

We claim:

l. A temperature control system for adjusting the positions of a plurality of shutters for controlling the delivery of lair to a selected location andincluding a pair of -mainshutters actuated by separate uid pressure motors and an auxiliary shutter cooperatively associated with both main shutters and actuated by a fluid motor, means for regulating the position of one main shutter and said auxiliary shutter in accordance with the temperature condition at one selected location, comprising a irst thermostat and relay circuits controlled thereby for regulating the flow of pressure fluid to a fluid motor associated with one main shutter and to theffduid motor associated with the auxiliary shutter, means for regulating the position of the other main shutter, comprising a second thermostat and relay circuits controlled thereby for regulating the flow of pressure iiuid to the iluid motor associated with the last mentioned main shutter, and means including additional relay circuits `associated with the second thermostat andselectively effective for controlling the now of pressure fluid vto the uid motor for adjusting the position or" said auxiliary shutter.

2. A temperature control system for adjusting the positions oi a plurality of vshutters for controlling the delivery of air to selected locations and` including a pair of main shutters actuated by separate fluid pressure motors and an auxiliary shutter cooperatively associated with both main shutters and actuated by a fluid motor, means for regulating the position of one main shutter and said auxiliary shutter in accordance with the temperature condition at one selected location, comprising a first thermostat and relay circuits controlled thereby for regulating the flow of pressure iiuid to a fluid motor associated with one main shutter and to the fluid motor associated with lthe auxiliary shutter, means for regulating the position of the other main shutter, comprising a second thermostat and relay vcircuits controlled thereby for regulating the flow of pressure fluid to the duid motor associated with the last mentioned main shutter and to the fluid motor associated with said auxiliary shutter, and means for preventing the change inposition of saidauxiliary shutter bythe last mentioned 'means when the first named means is regulating the position of said auxiliary shutter, comprising parallel circuits to regulate the iiow of pressure iluid to said auxiliary shutter iiuid motor, one of said parallel circuits being closed by the relay circuits controlled by said first thermostat.

3. In combination with a plurality of shutters for controlling the delivery of air to selected locations for maintaining predetermined temperatures at said locations, of means for adjusting the positions of said shutters to vary the amount of air delivered comprising separate uid pressure motors for actuating the shutters, a fluid pressure system comprising an electrically operated pump for supplying pressure uid to said uid pressure motors, means comprising a thermostat responsive to the temperature at one selected location and a pair of relays controlled thereby for controllingr the now of pressure fluid to two of said pressure motors so as to adjust the positions of the two shutters associated therewith, and means comprising a thermostat responsive to the temperature at another location and a pair of relays controlled thereby for controlling the flow of pressure fluid to another of said pressure motors and to one pressure motor of said pair; whereby one pressure motor of said pair may be selectively controlled by either thermostat through circuits connected through one of the relays controlled by such thermostat.

4. In combination with a plurality of shutters for controlling the delivery of air to selected locations for maintaining predetermined temperatures at such locations, of means for adjusting the positions of said shutters to vary the amount of air delivered comprising separate fluid pressure motors for actuating the shutters, a uid pressure system comprising an electrically operated pump for supplying pressure fluid to said fluid pressure motors, means comprising a thermostat responsive to the temperature at one selected location, a pair of relays controlled thereby and electrical circuit conductors connected in parallel through one relay of said pair for controlling the ilow of pressure fluid to two of said pressure motors so as to adjust the positions of the two shutters associated therewith, and means comprising a thermostat responsive to the temperature at another location, a pair of relays controlled thereby and electrical circuit conductors connected in parallel through one relay of the last mentioned pair for controlling the flow of pressure uid to another or said pressure motors and to one pressure motor of said pair; whereby one pressure motor of said pair may be selectively controlled by either thermostat through circuits connected through one of the relays controlled by each thermostat.

5. In combination with a plurality of valves for controlling the delivery of a temperature altering medium to maintain a predetermined temperature at selected locations, of means for adjusting said valves in response to said predetermined temperatures comprising separate fluid pressure motors connected to each of said valves, electrically actuated inlet and outlet valves for each fluid pressure motor, a thermostat responsive to the temperature at one selected location, a pair of relays including electrical energizing circuits therefor connected through said thermostat, means defining electrical energizing circuits for said inlet valves connected through one of said relays, means dening electrical energizing circuits for said outlet valves connected through the other relay, a second thermostat responsive to a predetermined temperature at another of said selected locations, a second pair of relays having their energizing circuits connected through the second thermostat, means connected through one relay of the second pair and defining an electric circuit for the inlet valve of one of said fluid pressure motors, and means connected through the other relay of the second pair and defining an electric circuit for the outlet valve of the last mentioned fluid pressure motor, whereby one of said fluid pressure motors may be selectively controlled in response to a predetermined temperature at either of said selected locations.

6. In combination with a plurality of shutters for controlling the delivery of air to selected locations for maintaining predetermined temperatures at said locations, of means for adjusting the positions of said shutters to vary the amount of air delivered comprising separate fluid pressure motors, each being operated in one direction by fluid pressure to impart an opening move ment to the shutters and operated in reverse direction by spring pressure to impart a closing movement to the shutters, an electrically operated inlet valve for each pressure motor to control the admission of pressure thereto, an electrically operated exhaust valve for each fluid motor to control the discharge of pressure fluid therefrom, a fluid pressure system comprising an electrically operated pump for supplying the pressure fluid to the inlet valves of all pressure motors, means comprising a first thermostat re-` sponsive to the temperature at a selected location, a first pair of relays controlled thereby and electrical circuit connectors connected in parallel through one of said relays for controlling the opening and closing of the inlet valves of two of said pressure motors so as to adjust the opening positions of the two shutters associated therewith, means comprising electrical conductors connected in parallel through the other relay of said pair for controlling the operation of the exhaust valves for said two pressure motors, and means comprising a second thermostat responsive to the temperature at yanother location, a pair of relays controlled thereby and electrical connectors connected in parallel 4through one relay of the last named pair for controlling the operation of the inlet valve of another pressure iluid motor and the operation of the inlet valve of one of the two previously named pressure motors to control the admission of fluid pressure thereto, means defining electrical circuits connected in parallel through the other of the last mentioned pair of relays for controlling the operation of the exhaust valves of the two last mentioned pressure motors, whereby the opening and closing adjustments of one shutter of the first pair may be selectively controlled by either thermostat and the relays associated therewith.

7. Apparatus for adjusting the positions of a plurality of air delivery shutters as defined in claim 6 characterized in that the said inlet valves are spring closed and electrically energized open and the exhaust valves are spring opened and electrically energized closed.

8. Apparatus for adjusting the positions of a plurality of air delivery shutters as defined in claim '7 characterized in that each thermostat is provided with spaced upper and lower contacts dening the upper and lower limits of a predetermined range, the upper contacts of each thermostat being connected in a shunt control circuit adapted to deenergize one of its associated relays, to close energizing circuits through the pressure motor inlet Valves, whereby the fluid pressure motors associated with said relays are operated in a direction to open the shutters; and the lower contacts of each thermostat'being normally connected in a shunt control circuit adapted to be opened, when the temperature falls below the lower limit of said temperature range, to permit the -exhaustvalves to open, whereby the iluid pressure motors are operated in a direction to close said shutters.

9. In combination with ya pair of main shutters for controlling thedelivery of air to the cooling systems of two engines and an auxiliary shutter for delivering additional airto thecooling systems of both engines, of iiuid pressure motors operable to `adjust the positions of said shutters to Vary the amount of air delivered in relation to the cooling-load, a iluid pressure systern comprising a motor and a pump operated thereby for supplying pressure fluid to said fluid motors, an inlet valve for each fluid motor to control the admission of pressure -iiuid thereto, an exhaust valve for each liuidmotor to control the porting ot Vpressure iiuidtherefrom,

means for regulatingI the position of oneA mainV shutter and said auxiliary shutter-inaccordance with the temperature condition of one engine, means for regulating.,thefposition oi the other main shutter andy said kauxiliary shutter in accordance with thetemperature condition of the other engine, and, 4means for preventingv Vthe change in position of said vauxiliary shutterk by said second named. means when saidnrst named means is regulating thepositionof said auxiliary shutter.

10. In combination with a pair of main shutters for controlling-the delivery of` air tothe cool-.

ing systems of two. engines andan auxiliary shutter for delivering additionalair to .thelcooling system of both engines, otiiuid pressure motors,

operable to adjust-the positions of. said shutters to vary the amount of,v air delivered. in relation to the cooling load, a fluidpressure. system. comprising a motor anda pumpoperated thereby for supplying pressure fluid to saidl uid motors, an inlet Valve for each fluid motor to control the admission of pressure uid thereto, an exhaust valve for each iiuid motor to control the porting of pressure duid therefrom, means for ,regulating the position of the. main shutter of one of said engines and said auxiliary shutter in accordance with the temperature condition of the said one engine, comprising a first thermostatand a pair of relays controlled. thereby, one of said relays closing a circuit to saidv motor and saidpump to supply pressure Iluidlto said first. main shutter fluid and said auxiliary shutter. fluid motor, said relay also closing circuits to said inlet valves for said main shutter fluid motor and said auxiliary shutter fluid motor, the. other oi said relays closing circuits to said exhaust, valves for said main and auxiliary shutter .fluid motors, means for` regulatingthe position of the main shutter of the other of said engines and said auxiliary shutter in accordance with the condition of the said other engine, comprising a second thermostat and a second pairr of relays controlled thereby, the first of said second pair ofA relays closing a circuit to said motor andsaid pump to supply pressure iiud to said second main shutter fluid motor and said auxiliary shutter fluid motor, said first relay of said second pairof relays also closing circuits to said inlet valves for said second main shutter fluid motor andr said auxiliary shutter uid motor,l the other of said second pair of relaysclosing circuits to said exhaust valves for said second main shutter and said auxiliary shutter iiuid'motors, and means for preventing the change in position of said auxiliary shutter by said second named means when said first named means is regulating the position of said auxiliary shutter.

11. In combination with a pair of main shutters for controlling the delivery of air to the cooling systems of `two engines and an auxiliary shutter for delivering additional air to the cooling system of both engines, of fluid pressure motors operable to adjust the positions of said shutters to vary the amount of air delivered in relation to the cooling load, a fluid pressure system comprising a motor and a pump operated thereby for supplying pressure fluid to said iuid motors, an inlet valve for each fluid motor to control the admission of pressure iiuid thereto, an exhaust valve for each fluid motor to control the porting of pressure fluid therefrom, `means for regulating the position of the main shutter of one of said engines and said auxiliary shutter in accordance with the temperature condition of the said one engine, comprising a `iirst 4thermostat and a pair of relays controlled thereby, one of said relays closing a circuit to said motor and said pump to supply pressure fluid to saidrst main shutter fluid and said f auxiliary shutter fluid motor, said relay also closing circuits to said inlet valves for said main shutter fluid motor and said auxiliary shutter nuid motor, the other of said relays closing circuits to said exhaust valves for said main and auxiliary shutter iiuid motors, means for regulating the position-of the -main shutter of the other ofsaid engines and said auxiliary shutter in accordance with the condition of the said other engine,V comprising a second thermostat and a second pair of relays controlled thereby, the first of said second/pair of relays closing a circuit tof said motor-and said pump to supply pressure fluid to said second main shutter fluid motor and said auxiliary shutter fluid motor, said first f relay of saidsecond pair of relays also closing circuits to said inlet valves forsaid second main shutter fluid .motor and saidv auxiliary shutter fluid motor, thel other of said second pair of relays closing circuitslto said exhaust valves for said. second main shutter and said auxiliary shutter fluid motors, and meansfor preventing the change in position of said auxiliary shutter by said second named means when said rst named means is regulating the position of said auxiliary shutter, comprising parallel circuits to regulate the flow of pressure fluid to said auxiliary vshutter iiuid motor, one of said parallel circuits including parallel circuits to said pump drive motor, the second of said parallel cir,- cuits including parallel circuits to said auxiliary shutter fluid motor inlet valve, and another of said parallel vcircuits including parallel circuits to said auxiliary shutter fluid motor exhaust valve.

References Cited in thele of this patent UNITED STATES PATENTS Number Name Date 2,112,998 Ray Apr. 5, 1938 2,153,382 Martin Apr. fi, 1929 2,235,620 Nessell Mar. 18, 194]. 2,336,840 Brehob Dec. 14, 1943. 2,401,004 Lehane May 28, 1946 

